36 A STUDY OF WHEAT. 



We have now some wheat flour, in which we suspect is 

 potato starch or something else of a foreign nature. We will 

 take up a little of the flour on the point of the penknife, 

 placing it in a drop of water which has previously been placed 

 on the glass slide and carefully covering it with the thin cover 

 glass, when it is ready to study under the microscope. Exam- 

 ining some of the flour taken from several different parts of 

 the specimen will generally be sufficient. This is the simplest 

 and most convenient method of work, and does away with the 

 long preparation, in which so many seem to delight. However, 

 if very critical study of a specimen of flour be desired, per- 

 haps the best method is that given by M. Boland, American 

 Miller, August, 1878, page 183. Take a small amount of flour 

 and add to it half its weight of water, to make a 

 paste. Work this paste in the hollow of the hand, plunging 

 it from time to time in a basin half full of water, slightly 

 warmed. When lumps are no longer felt in the dough, wash 

 the membraneous substance which remains in the hand under 

 a stream of water, and when the water escapes clear the pure 

 gluten is obtained. If there be any doubt of this, you have 

 only to touch it with an alcoholic solution of iodine, and if it 

 turns blue at the point of contact, starch is yet present; if it 

 shows only a yellow color, you may be satisfied of its purity. 

 Take the water used in washing the gluten, at the bottom of 

 which a solid deposit has already been formed, and agitate it 

 in order to place all the particles in solution again. Then 

 pour it over a metal sieve into a conical-shaped glass vessel. 

 Let the water which the vessel contains stand an hour. A de- 

 posit will then have formed in the bottom which must not be dis- 

 turbed. Remove the water from this deposit with a siphon, and 

 two hours later draw off the water again, which is still pro- 

 duced from the mass from time to time, until only a deposit 

 remains, composed of two distinct layers. The upper one will 

 have a grayish color, and is composed of gluten, of albumen, 

 and of a sugary substance. The other layer will have a dull, 

 white color, and is starch. Some time afterward carefully re- 

 move the upper layer with a teaspoon and allow the lower one 

 to dry. The drying process may be facilitated by placing bits 

 of blotting paper on the starch. When it is dry the starch 



